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/*
* Driver for pcf857x, pca857x, and pca967x I2C GPIO expanders
*
* This code was ported from linux-5.1 kernel by Michael Grzeschik.
*
* Copyright (C) 2007 David Brownell
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#include <common.h>
#include <malloc.h>
#include <driver.h>
#include <xfuncs.h>
#include <errno.h>
#include <i2c/i2c.h>
#include <gpio.h>
static const struct platform_device_id pcf857x_id[] = {
{ "pcf8574", 8 },
{ "pcf8574a", 8 },
{ "pca8574", 8 },
{ "pca9670", 8 },
{ "pca9672", 8 },
{ "pca9674", 8 },
{ "pcf8575", 16 },
{ "pca8575", 16 },
{ "pca9671", 16 },
{ "pca9673", 16 },
{ "pca9675", 16 },
{ "max7328", 8 },
{ "max7329", 8 },
{ }
};
/*
* The pcf857x, pca857x, and pca967x chips only expose one read and one
* write register. Writing a "one" bit (to match the reset state) lets
* that pin be used as an input; it's not an open-drain model, but acts
* a bit like one. This is described as "quasi-bidirectional"; read the
* chip documentation for details.
*
* Many other I2C GPIO expander chips (like the pca953x models) have
* more complex register models and more conventional circuitry using
* push/pull drivers. They often use the same 0x20..0x27 addresses as
* pcf857x parts, making the "legacy" I2C driver model problematic.
*/
struct pcf857x {
struct gpio_chip chip;
struct i2c_client *client;
unsigned out; /* software latch */
int (*write)(struct i2c_client *client, unsigned data);
int (*read)(struct i2c_client *client);
};
static inline struct pcf857x *to_pcf(struct gpio_chip *gc)
{
return container_of(gc, struct pcf857x, chip);
}
/*-------------------------------------------------------------------------*/
/* Talk to 8-bit I/O expander */
static int i2c_write_le8(struct i2c_client *client, unsigned data)
{
return i2c_smbus_write_byte(client, data);
}
static int i2c_read_le8(struct i2c_client *client)
{
return (int)i2c_smbus_read_byte(client);
}
/* Talk to 16-bit I/O expander */
static int i2c_write_le16(struct i2c_client *client, unsigned word)
{
u8 buf[2] = { word & 0xff, word >> 8, };
int ret;
ret = i2c_master_send(client, buf, 2);
return (ret < 0) ? ret : 0;
}
static int i2c_read_le16(struct i2c_client *client)
{
u8 buf[2];
int ret;
ret = i2c_master_recv(client, buf, 2);
if (ret < 0)
return ret;
return (buf[1] << 8) | buf[0];
}
/*-------------------------------------------------------------------------*/
static int pcf857x_input(struct gpio_chip *chip, unsigned offset)
{
struct pcf857x *gpio = to_pcf(chip);
int ret;
gpio->out |= (1 << offset);
ret = gpio->write(gpio->client, gpio->out);
return ret;
}
static int pcf857x_get(struct gpio_chip *chip, unsigned offset)
{
struct pcf857x *gpio = to_pcf(chip);
int value;
value = gpio->read(gpio->client);
return (value < 0) ? value : !!(value & (1 << offset));
}
static int pcf857x_output(struct gpio_chip *chip, unsigned offset, int value)
{
struct pcf857x *gpio = to_pcf(chip);
unsigned bit = 1 << offset;
int ret;
if (value)
gpio->out |= bit;
else
gpio->out &= ~bit;
ret = gpio->write(gpio->client, gpio->out);
return ret;
}
static void pcf857x_set(struct gpio_chip *chip, unsigned offset, int value)
{
pcf857x_output(chip, offset, value);
}
/*-------------------------------------------------------------------------*/
static struct gpio_ops pcf857x_gpio_ops = {
.direction_input = pcf857x_input,
.direction_output = pcf857x_output,
.get = pcf857x_get,
.set = pcf857x_set,
};
static int pcf857x_probe(struct device_d *dev)
{
struct i2c_client *client = to_i2c_client(dev);
struct device_node *np = dev->device_node;
struct pcf857x *gpio;
unsigned long driver_data;
unsigned int n_latch = 0;
int ret;
if (!np)
return -EINVAL;
of_property_read_u32(np, "lines-initial-states", &n_latch);
/* Allocate, initialize, and register this gpio_chip. */
gpio = xzalloc(sizeof(*gpio));
ret = dev_get_drvdata(dev, (const void **)&driver_data);
if (ret)
return ret;
gpio->chip.base = -1;
gpio->chip.ops = &pcf857x_gpio_ops;
gpio->chip.ngpio = driver_data;
gpio->chip.dev = &client->dev;
/* NOTE: the OnSemi jlc1562b is also largely compatible with
* these parts, notably for output. It has a low-resolution
* DAC instead of pin change IRQs; and its inputs can be the
* result of comparators.
*/
/* 8574 addresses are 0x20..0x27; 8574a uses 0x38..0x3f;
* 9670, 9672, 9764, and 9764a use quite a variety.
*
* NOTE: we don't distinguish here between *4 and *4a parts.
*/
switch (gpio->chip.ngpio) {
case 8:
gpio->write = i2c_write_le8;
gpio->read = i2c_read_le8;
break;
/* '75/'75c addresses are 0x20..0x27, just like the '74;
* the '75c doesn't have a current source pulling high.
* 9671, 9673, and 9765 use quite a variety of addresses.
*
* NOTE: we don't distinguish here between '75 and '75c parts.
*/
case 16:
gpio->write = i2c_write_le16;
gpio->read = i2c_read_le16;
break;
default:
dev_warn(&client->dev, "unsupported number of gpios\n");
return -EINVAL;
}
gpio->client = client;
/* NOTE: these chips have strange "quasi-bidirectional" I/O pins.
* We can't actually know whether a pin is configured (a) as output
* and driving the signal low, or (b) as input and reporting a low
* value ... without knowing the last value written since the chip
* came out of reset (if any). We can't read the latched output.
*
* In short, the only reliable solution for setting up pin direction
* is to do it explicitly.
*
* Using n_latch avoids that trouble. When left initialized to zero,
* our software copy of the "latch" then matches the chip's all-ones
* reset state. Otherwise it flags pins to be driven low.
*/
gpio->out = ~n_latch;
ret = gpiochip_add(&gpio->chip);
if (ret)
return ret;
return ret;
}
static const struct of_device_id pcf857x_dt_ids[] = {
{ .compatible = "nxp,pcf8574", .data = (void *)8 },
{ .compatible = "nxp,pcf8574a", .data = (void *)8 },
{ .compatible = "nxp,pca8574", .data = (void *)8 },
{ .compatible = "nxp,pca9670", .data = (void *)8 },
{ .compatible = "nxp,pca9672", .data = (void *)8 },
{ .compatible = "nxp,pca9674", .data = (void *)8 },
{ .compatible = "nxp,pcf8575", .data = (void *)16 },
{ .compatible = "nxp,pca8575", .data = (void *)16 },
{ .compatible = "nxp,pca9671", .data = (void *)16 },
{ .compatible = "nxp,pca9673", .data = (void *)16 },
{ .compatible = "nxp,pca9675", .data = (void *)16 },
{ .compatible = "maxim,max7328", .data = (void *)8 },
{ .compatible = "maxim,max7329", .data = (void *)8 },
{ }
};
static struct driver_d pcf857x_driver = {
.name = "pcf857x",
.probe = pcf857x_probe,
.of_compatible = DRV_OF_COMPAT(pcf857x_dt_ids),
.id_table = pcf857x_id,
};
device_i2c_driver(pcf857x_driver);
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